langlois 1-- If your rear brake pedal is hard and the rear brake pads are not activating against the rear brake rotor, you may have a piece of debris stuck in the master cylinder; or an air lock which is compressing air against the flow of brake fluid.
You said you bled the rear brake system twice so it could be you still have air in the system. You could try this:
obtain a clean empty clear bottle or jar and put some clean brake fluid into it.
fit a clean small diameter hose onto the bleed nipple at the rear brake caliper, and run the hose into the jar MAKING SURE the end of the hose stays in the brake fluid in the jar. You can add more fluid if the hose tries to come out of the bottle or jar.
with the correct size spanner slightly open the bleed nipple and press the brake pedal down, and when you get the pedal near the bottom of the stroke (near the footboard) close the bleed nipple then let the pedal return to the 'up' position.
repeat the process again and again until no air bubbles are seen coming from the bottle.
You MUST:
make sure you keep topping up the brake fluid in the master cylinder between bleeds and make sure the small hose stays in the fluid in the bottle or jar.
IF you open the bleed nipple and press the brake pedal down but it doesn't move, then you probably have a piece of debris blocking the master cylinder or in the brake line. If this is the problem, you will need to remove the master cylinder, take it apart, and clear the debris and/or install a rebuild kit in the master cylinder if the piston "O" rings are damaged, OR if it's in the brake line remove it and blow it out with compressed air.
Once you have no blockage, reassemble the system and bleed it as per the method above.
Let us know how it goes.